What's this?It's a box.为什么回答中要用It's,而不用this is a box

问题描述:

What's this?It's a box.为什么回答中要用It's,而不用this is a box

It is a box.是强调‘箱子’不是别的什么东东
This is a box.是强调 ‘这(this)’ 而不是‘那(that)’